Moreover, Feinberg found that each individual grain in the rock is magnetized in the same direction, meaning that the rock has not been broken up and reformed since it was deposited. This makes extremely unlikely the possibility that the original ash had been weathered into sand that early humans walked through before the sand was welded into rock again.
"Imagine two-millimeter-wide BBs cemented together where they're touching," Feinberg said. "The paleomagnetic data tell us that these things did not move around at all since they were deposited. They haven't been eroded and redeposited anywhere else. They fell while they were still hot, which raises the question of the validity of the footprints. If they were hot, why would anybody be walking on them?"
The British researchers, funded by the United Kingdom's Natural Environment Research Council, have promoted their hypothesis widely, most prominently at a July 4, 2005, presentation and press conference at the Royal Society's Summer Science Exhibition 2005 in London. The team, which includes Gonzalez as well as Professor David Huddart from John Moores University, also involves scientists from Bournemouth University, the University of Oxford and the Australian National University. They have yet to publish a peer-reviewed analysis of the footprints.
In all, the British team claims to have found 250 footprints - mostly human, but also dog, cat and cloven-hoofed animal prints - in a layer of volcanic ash deposited in a former lake bed now exposed near a reservoir outside Puebla. Its dating techniques returned a date of 40,000 years ago, in contrast to the oldest accepted human fossil from the Americas, an 11,500-year-old skull. This makes the rock "one of the most important areas in the study of early human occupatio
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Source:University of California - Berkeley